I stood in a huge hangar at Pinewood Studios and watched as a team of carpenters hammered away, putting up beams and drywall. Electricians were running cables.

Two men were moving a big fireplace into position. Others were discussing what colour to paint the kitchen. They were, effectively, building a couple of flats from scratch.

Meanwhile, upstairs in another studio, another team of technicians were building a detailed, full-size replica of the office I used to work in nearly 20 years ago.

Across the lot, in the real offices, as opposed to the made-up ones, there was a room for props and wardrobe and make-up, a room for the producer and director, for the location manager, a communal area with half a dozen desks, a photocopying room, and an accountant’s office.

There were dozens of people scurrying back and forth, asking questions and answering phones. There was a catering van serving hot food from 7am.

All of this was happening because, nearly 10 years ago, I sat in a room on my own and typed a sentence that began, “I’m standing at my office window, smoking...”

Yes, after several years in development, the movie of my first novel Kill Your Friends started shooting last Monday.

The film is set in 1997 and stars Nicholas Hoult (Skins, A Simple Man, X-Men) as 26-year-old A&R man Steven Stelfox, a psychopath hell bent on (literally) slashing his way to the top of the music industry.

There’s also a great ensemble cast including James Corden, Joseph Mawle (Game of Thrones), Craig Roberts (Submarine, 22 Jump Street) and Edinburgh’s very own Georgia King (Chalet Girl, Cockneys v Zombies).

As some of you may know, in addition to writing books I also earn a crust as a screenwriter, so it’s not the first time I’ve been on a film set, but it’s really something to see your own novel, and one that frames 10 years of the lives of you and your friends, become a movie.

The experience has also brought home one of the big differences between writing novels and screenplays for a living.

A novel, of course, is a fully self-contained work of art. You pick it up off the shelf, open it and there it is – a whole universe waiting for you to enter.

A screenplay is just a blueprint for making a movie. Until the movie is actually filmed, the script really means nothing.

When you work on screenplays that never get filmed (and I know many writers who make a very good living this way, hundreds of movies are developed every year and very few go into production) it is like you are an architect who is forever designing buildings that never get constructed. It is financially rewarding, but creatively frustrating.

It’s also brought home to me the practicalities of movie making.

I was asked at one point if the dog in a scene could be awake rather than asleep. “Sure,” I said.

It turned out they might use a different dog if it was awake rather than asleep and the dog handler had to know which dog to prepare.

“Dear God,” you think. “All of this because I typed the words, ‘A dog is asleep on the sofa.’”

I pictured a whole world of wee dog prima donnas, all with their own managers and agents and demands for bigger trailers and stuff.

It was also very pleasing, from a practical point of view, to sit in a production meeting and hear the words, “OK, so for that scene we’re going to need cocaine, a severed limb, a urine rig and lots of blood.”

I held my hand up at that point and said: “I am John Niven and I deeply apologise for all this filth.”

Someone once wrote that “there is no stranger country than the recent past”. 1997 is not so long ago for some of us, yet it already feels like another era.

It certainly does for much of the cast, many of whom were born in the 90s, who were just small children when I was blasting my way through some of the events they are portraying.

I went along to the first day of filming, just to hear them shout, “Action!” for the first time.

But being on the set is difficult for a writer. Your job is done and it is in the hands of the director. (Thankfully, the director of Kill Your Friends, Owen Harris, has worked on Black Mirror and Holy Flying Circus and is brilliant.)

In the end being the writer on set is a bit like having organised a big party but you’re not allowed to eat or drink anything. You just have to stand in the corner.

If you follow me on Twitter you’ll know I expressed this sentiment earlier in the week, but in more, ah, robust language.

So I’ll leave them to it for the next five weeks. Break a leg guys. All being well we’ll get to see the results in the cinema, about this time next year.

When I’ll be the one at the back, shouting “I am John Niven and I deeply apologise for all this filth.’